short circuit protection for balanced

Posted on Feb 4, 2014

This circuit was designed to protect a dual rail power supply from shorts across the two rails. It uses an optocoupler to monitor each supply rail, with the internal LEDs powered from ZD2 and ZD3 and the associated resistors. While the LEDs are on, the optocouplers internal transistors are both turned on which ensures that transistor Q1 is on and

short circuit protection for balanced
Click here to download the full size of the above Circuit.

relay RLY1 is energised. If either rail is short-circuited, the associated optocoupler is turned off, robbing Q1 of base current and the relay then drops out to disconnect the supply rails. Operation is restored by pressing the reset button. The value of ZD1 and the associated resistor should be chosen to suit the supply and relay coil voltages.

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Compressor-Limiter-Clipper for FM transmitters
    Colpitts oscillator FM transmitter
    Step sequencer
    led light flasher
    Speed-Limit Alert
    Most Popular Circuits
    Wide band high frequency amplifier circuit
    Gentle Breeze
    hartley oscillators
    The local oscillator for 10.7 to 2.5MHz conversion
    Fast charging circuit TEA1102